Your body is constantly expending energy—even when you’re sitting still. Everything from breathing to digesting food to simply maintaining organ function requires calories. Whenever you add physical activity, whether it’s hitting the gym or tackling household chores, you ramp up your calorie burn. Together, these components make up your Total Daily Energy Expenditure, or TDEE.
“Total daily energy expenditure stands for the total number of calories your body needs daily to keep your weight stable,” explains Michael Richardson, MD, a Boston-based family physician focused on sports medicine and fitness. “It includes what you burn at rest—your basal metabolic rate—plus the calories you use during all forms of activity.”
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Dr. Richardson stresses that knowing your TDEE is key to managing your weight, whether you hope to lose, gain, or maintain. Below we’ll look at how TDEE works, how you can estimate it, which factors impact your daily burn, and what to do once you know your number.
What Is TDEE?
TDEE is the total energy, expressed in calories, that you expend in a single day, explains Theresa Gentile, RDN, a registered dietitian in Brooklyn and a spokesperson for the Academy of Nutrition and Dietetics.
There are three basic components to your TDEE:
- The energy your body needs for vital life processes, like keeping your heart beating and your lungs working—even when you’re at rest—accounts for the largest portion of your TDEE, says Gentile.
- The calories required to break down and process the food you eat.
- The energy you spend moving, which includes both structured exercise and simple activities like walking or fidgeting.
What Factors Influence It?
As Dr. Richardson points out, a range of elements can affect your TDEE: some are within your control, others are not, and certain ones you can influence over time.
For example, you have complete control over your activity level—choosing to move more means you’ll use more energy. But factors like your age, genetics, and hormonal balance are out of your hands. You can, however, work on increasing your muscle mass, which raises your resting calorie burn.
“That’s why I recommend that my patients prioritize strength training for weight loss, instead of relying solely on cardio routines,” Dr. Richardson says.
Age is significant as well: your basal metabolic rate (BMR) typically decreases as you get older, notes Gentile. Your daily movements and diet also make a difference—digesting protein, for instance, requires more energy than digesting fat or carbohydrates.
How to Calculate Your TDEE
You’ll find plenty of online tools to estimate your TDEE, which take into account age, height, weight, gender, and activity level.
Here’s one example of a TDEE calculator you can try.
To illustrate, a 40-year-old man who stands 180cm tall, weighs 91kg, and gets moderate exercise will have an estimated TDEE of about 2,850 calories per day. That means he’d need to eat approximately 2,850 calories daily to keep his current weight steady.
Gentile points out that while online calculators are usually pretty accurate for most people, they’re still estimates. “True calorie needs depend on factors like muscle mass, hormones, and genetics, which these tools aren’t able to measure,” she says. She also cautions that people often misinterpret their activity levels, which can vary significantly from day to day.
Another limitation, as Dr. Richardson notes: calculators only consider total body weight and not the breakdown between fat and muscle—a critical element for accuracy. For a better estimate, he suggests body composition testing, which measures fat, bone, and muscle percentages.
Why Knowing Your TDEE Matters
Once you’re aware of your TDEE, you have valuable insight into how many calories your body actually needs to maintain your present weight, says Gentile. It becomes a solid starting point for any diet or lifestyle change. “With this information, you can adjust different factors to help reach your specific goals,” she adds.
If your aim is to build muscle, you’ll need to eat more than your TDEE and create a calorie surplus, explains Dr. Richardson—giving your body what it needs for repair and muscle growth. For weight loss, you’d eat slightly less than your TDEE. “I often figure out TDEE for patients who feel stuck with their weight loss efforts,” Dr. Richardson says. “It’s common for people to overestimate their needs and unintentionally eat too much.”
However, Dr. Richardson has also seen an increase in people—especially those using GLP-1 medications (like Ozempic) to curb appetite—consuming far fewer calories than their TDEE. “This can lead to what’s known as metabolic adaptation,” he says, “where your body slows down your natural TDEE in response to under-eating, making progress even harder.” Many patients are surprised when he recommends eating more to restore their metabolism, only to find that, as a result, their weight loss resumes. If you’re unsure how to assess or use your TDEE, consider seeking guidance from your doctor or a certified dietitian.
